Method of recovering sulfate crystals.



' PATENTED JUNE 25, 1907.

P. H..DANIELS, A. F. BAGKLING: H. KVSWINSGOE. METHOD OF RBGOVERING SULFATE CRYSTALS.

APPLIOATIOHIILED APR. 2, 1906. v

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mven W W1 2% Tons WITNESSES No. 857,793. PATENTEDJUNE 25, 1907. F. H. DANIELS, A. F. BAGKLIN & H. SWINSGOE. METHOD OF REGOVERING SULFATE CRYSTALS.

APPLICATION FILED APR. 2 1906.

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WITNESSES INVENTORS.

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PATENTED JUNE 25, 1907.

K. SWINSCOE'.

F. H. DANIELS, A. F. BAGKLIN & H.

METHOD OF REGOVERING SULFATE CRYSTALS.

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APPLICATION FILED APR. 2,1906.

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WITN ESSES PATENTED JUNE 25, 1907. A. P. BAGKLIN & H. K. swmscoa. METHOD OF REGOVERING SULFATE CRYSTALS.

F. H. DANIELS APPLIOATION FILED APR. 2.1906.

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WITN ESSES 78% wmLwa/kfl UNITED STATES PA TENT OFFICE.

FRED DANIELS, AXEL F. BACKLIN, AND HENRY K. SWINSCOE, OF WORCES TER, MASSACHUSETTS, ASSIGNORS TO AMERICAN STEEL AND WIRE COMPANY, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF NEW JERSEY.

METHOD OF RECQVERING SULFATE CRYSTALS.

Specification of Letters Patent.

Application filed an 2,1906. Serial No. 309,321.

To all whom it may concern:

Be it known that we, FRED H. DANIELs, AXEL F. BAGKLIN, and HENRY K. SwINscoE, of Worcester, Massachusetts, have invented a new and useful Method of Recovering Sulfate Crystals, of which the following is a specification, reference beinghad to the accompanying drawing, in which Figure 1 1s a plan view showing one form of apparatus for carrying out our invention; Fig. 2 is a vertical section on the line A-A of Fig. 1; Fig. 3 is a side elevation, partly broken away showing the multiple effects;

Figs. 4 and 5 are respectively a lan view I 5 and an elevation showing a modifie arrangement of the tanks and'conveye'rs.

The purpose of our invention is to provide a cheap and efficient process for recovering sulfate of iron fi'o'mthe liquor which results from the pickling of iron or steel wire, rods,

plates, sheets, etc., in an acid bath.

The object of the invention is to provide a process by. which a valuable commercial roduct may be obtained from this liquor in 5 arge amounts and at small expense.

The invention is also applicable with suitable changes in the materials of the apparatus, to the recovery of sulfate of copper .from the liquor resulting from the pickling of 3 co per, rods, etc.

n the practice of our invention, we take the sulfate liquor from the pickling vats and deliver it to suitable stora e tanks 2 in which it is neutralized by the ad ition of waste iron 3 5 or steel wire or other iron or steel scrap. These tanks are referably provided with steam coils 2 to eat the solution somewhat in order to prevent premature crystallizing in the tanks.

When the solution becomes neutralized, that is to say, when the free acid has been substantially satisfied by the iron with which it comes in contact, it is removed by suitable pumps into a settling-tank 3 in which the 5 mechanical impurities present in the liquor are settled by gravity, and from this settlingtank the solution is drawn successively into vacuum evaporators 4, 4;, 4, known 1n the art as multiple effects. A suitable number of these effects may be employed. Each one contains'tubes preferably made of copper, and the effects are provided with vacuumroducing apparatus.

The di ute neutralizedjiquor is supplied to the first effect, where it comes in contact with and circulates within or around the copper tubes, which are filled with or are surrounded by a heating medium, and in this effeet a art of the water passes off in the form of vapor. The liquor then asses to the second effect, in which it is furt er evaporated, and in the same manner to the other Patented June 25, 1907.

effect or effects, where it is finally concentrated. The steam for supplying the coils of the first efiect may be exhaust steam or live steam supplied from an outsidesource, and the steam for the heating-coils of the second effect may be obtained by utilizing the vapor generated by the boiling of the liquor in the first effect. In the same manner the vapor from the second efiect may be passed'to the coils of the third effect, and so on, the vapors from the liquor in the final effect being passed into j a suitable condenser equipped with a vacuum pump, From the final effect the concentrated liquor 'is delivered by 'a pump 5 either to the preliminary cooler or settling-tank, or directly into a number of crystallizing-tanks which may be located on a lower floor.

If the intermediate cooler is employed, it may consist as shown, of a conical shell or dome 6 of steel or iron, which may be cooled in any suitable manner, as by an air blast beneath it. The liquor in passing over this dome loses a ortion of'its heat and consequently crysta lizes more readily, and is then passed to the crystallizing-tanks through ipes 7-7. The tank shown as a cooler may be used only as a settling-tank, as described, thus avoiding the forming of crystals in the pipes which convey the liquor therefrom to the crystallizing-tanks.

The crystallizing-tank's 8, 8 may be of any desirable form, such as round, rectangular, or square, and across the tops are laid planks or boards 9, from which are suspended a large number of thin iron slabs or plates 10. These plates referably extend vertically and reach nearfy to the bottoms of the tanks. The crystals form on these slabs as well as on the sides of the tanks, and the mother liquor is then drawn oif and returned to the storage tanks, after which the crystals are preferably shoveled by hand from the crystallizingtanks on to suitable conveyers 10 and 11 extending between the rows of tanks.

In Figs. 4 and 5 we show a modified arra ement of the tanks and conveyers in which the conveyers 12 and 13 discharge upon a cro s-conveyer 14. This conveyer again delive s the crystals to an inclined conveyer 15, which discharges into a hopper 1 6 provided with spouts and gates through which the ma' terial may be char ed into any desired number of centrifugal driers 17. i The larger percentage of moisture may be drawn off from the crystals by centrifugal force in these driers, which may be of any desirable and well known type. The dried crystals are dropped from the bottoms of the centrifugal 1ers upon an inclined conveyer 18, which in turn delivers them to an overhead conveyer 19 arranged so that the crystals can be unloade into any of a series of bins. From these bins the crystals may be drawn off through spouts to the railroad cars orcharged into barrels in the building.

The process above described is simple and efficient. The crystals are obtained cheaply and in large quantities, and contain a minimum of moisture, and the apparatus which we employ enables the operation to be carried on continuously and with little hand labor.

We do not claim herein theapparatus disclosed, as this is reserved for, and forms the subject-matter of our divisional co-pending application No. 329,002, filed August 3rd, 1906, for apparatus for recovering sulfate crystals.

Within the scope of our invention as stated in the claims, many changes maybe made in the form and arrangement of the apparatus and in the steps of the process. Some of the steps of the process may be employed without others, or may be employed 1n other combinations, since what we claim is:

1. A process of obtainin in a continuous manner a crystalline meta lic sulfate which consists in at least partially neutralizin an acid solution of a metallic sulfate by ad ing the same metal as the base of the sulfate, transferring the solution to a separate vessel where the impurities separate and then withdrawing and evaporatin the solution in a vacuum to the crysta point, then stantially as described.

2. A process of obtaining in a continuous manner a crystalline metallic sulfate which consists in at least partially neutralizing an acid solution of ametallic sulfate by adding the same metal as the base of the sulfate, maintaining such solution at a temperature above the crystallizing point, then evaporating the solution in a vacuum to the crystallizing point, and then transferring it to a crystallizing tank; substantially as described.

3. A process of obtaining in a continuous manner a crystalline metallic sulfate which consists in at least partially neutralizing an acid solution of a metallic sulfate by adding the same metal as the base of the sulfate, transferring the solution to a separate vessel where the impurities separate and then continuously feeding the neutralized solution by gravity and evaporating the solution in a vacuum to the crystallizing point, then transferring it to a crystallizing tank; substantially as described.

4. A process of obtainin in a continuous manner a crystalline meta lic sulfate which consists in at least partially neutralizing an acid solution of a metallic sulfate b adding the same metal as the base of the sul ate, continuously withdrawing the treated solution and concentrating it to the crystallizing point in successive steps under vacuum while maintaining a substantially constant current in the solution and then transferring the concentrated solution continuously to crystallizing tanks; substantially as described.

5. A process of obtaimng in a continuous manner a crystalline metallic sulfate which consists in at least partially neutralizin an acid solution of a metallic sulfate by adding the same metal as the base of the sulfate, continuously withdrawing and hot concentrating the solution under vacuum, and transferring the concentrated solution to crystallizing tanks in a substantiall continuous manner; substantially as descri ed.

In testimony whereof, We have hereunto set our hands.

FRED H. DANIELS. AXEL F. BACKLIN. HENRY K. SWINSOOE.

Witnesses WM. A. BACON, H. M. LATHAM.

transferring it to a crystallizing tank; sub- 

